Claire Currie
Department of Physics, University of Alberta
Tittle: Missing mountain roots: Geodynamic studies of lithosphere removal

Mountain belts generally correspond to areas of thickened continental crust. Indeed, the central Andes of South America is a high-elevation plateau (~4 km above sea level) that has a 50-70 km thick crust. Crustal thickening during mountain-building should be accompanied by thickening of the underlying mantle lithosphere. However, geophysical studies show that the mantle lithosphere below the central Andes is anomalously thin or absent, leading to the proposal that the dense lower lithosphere has undergone gravitational removal. In this talk, I will present numerical models that explore the dynamics of lithosphere removal. The models highlight the different styles of removal and the associated surface expressions, including surface topography, magmatism and crustal deformation. For the central Andes, episodes of lithosphere removal over the last 20 Ma can explain patterns of magmatism and the occurrence of “bobber basins”, which are short-lived, ~100 km wide basins found throughout the plateau.

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